Pumps and compressors of the flexible-tube type



A ril 4, 1961 A. SEYLER PUMPS -AND COMPRESSORS OF THE FLEXIBLE-TUBE TYPEFiled Feb. 1, 1957 2 Sheets-Sheet 1 L. A. SEYLER April 4, 1961 PUMPS ANDCOMPRESSORS OF THE FLEXIBLE-TUBE TYPE 2 Sheets-Sheet 2 Filed Feb. 1,1957 -the tube with increased PUNIPS AND COMPRESSORS OF THEFLEXIBLE-TUBE TYPE I Leon Antoine Seyler, 7 Rue Roy, Paris, France FiledFeb. 1, 1957, Ser. No. 637,783 Claims priority, application France Feb.10, 1956 10 Claims. Cl. 103-149 This invention relates to fluiddisplacement devices, i.e. pumps and compressors, of the type whereinthe fluid is propelled by the squeezing action of, a flexible tube withresiliently deformable walls through which the fluid flows,

the walls of the tube being cyclically compressed or flattened in orderto impart the desired displacement to the fluid. In one known form ofconstruction of such devices, the flexible tube is arranged in anarcuate path within a casing in which one or more squeezer rollersengaging the tube wall is or are rotated about an axis coincident withthe center of said arcuate path, so that at each rotation the rollerwill act to propell the fluids within the tube before it. 7 p

Pumps of this general character have many important advantages,including the fact that the displaced fluid is at no time brought intocontact with any metallic parts such as pistons, vanes or rotors;moreover the deliveryof such a pump can, theoretically at least, becontrolled with high accuracy over a wide range.

Such pumps have heretofore been open'to the drawback that the flexibletube becomes rapidly worn and re quires frequent replacement. It istherefore a general object of this invention to provide a fluiddisplacement has been heretofore the case.

Generally speaking there are several ways in which the engagement of theroller with the tube acts to subject the tube to objectionable wear andtear.

7 United States Patent O Patented Apr. 4, 1961 be imparted to the tubewithout subjecting the ridge and the tube wall to objectionablestresses. According to further features of the invention, the tube isintegrally formed with end flanges for retaining it against longitudinaldisplacement, and with reenforcing bosses or projections. In amodifiedform of the invention, the tube may comprise only a single flange at oneof its ends to facilitate its'insertion and removal intoand from thecasing, the casing being constructed in two sections adapted to bereadily opened apart and closed with respect to each other for insertionand removal of the tube. Further, the invention may include theprovision of means within the casing for damping the deformations of thetube,

which means comprise an auxiliary tube having one end open to atmosphereand its other end opening, within the.

casing. According to another feature, the casing may be formed withexpansion chambers adjacent to the opposite ends of the tube tofacilitate the expansion of the latter.

The above and further objects, advantages and features of the inventionwill become apparent as the description proceeds with reference to theaccompanying drawings, given by way of illustration but not oflimitation, and

wherein:

Fig. l is a side view of a flexible tube element according to theinvention, formed with a cross-cut retainer ridge, end retainer flanges,and bosses according to the invention;

Fig. 2 is a top plan view of Fig. 1;

Fig. 3 illustrates schematically the general lay-out of the device forvarying the fluid pressure, the casing being removed; v

Fig. 4 is an axial sectional view of a modified tube V l according tothe invention, the tube being shown in posidevice of the type described,wherein the deformable tube element will have a considerably longerservice life than (a) First, the tube tends to' be driven longitudinallyA by the roller, tending to be pushed into the casing at the inlet sideand to be pulled out of the casing at the outlet side.

(b) The tube maybe subjected to torsional strain twist ing it within itsrecess.

(c) At the point of initial engagementof the roller with the tube, thetube is subjected to an impact due, in the first place, tothe fact thatthe roller'compresses it suddenly at said point, and secondly, to thefact that the roller is allowed to revolve freely about its axis overtheidling part, of the rotational cycle so that-the roller, at the initialpoint ofthe active portion ,ofeach lcycle, strikes rotational energydueto itssaid free'rotatiomm (dlAdditional and high stressesare.developed'in the tubeas a roller disengages it atEtheYend-bflthe activeP01? tion of the cycle and'as the tube-suddenly springs back to itsinitial open shape.

Specific objects of the invention; accordingly, lie in preventing orminimizing any or all of the above objecridge for retaining the.tube'againstlateral displacement,

the ridge being formed with a plurality of transverse cuts orseparations so as to, allow the .requi te curvature to tion in thecasing;

Fig. 5 is an end view of the pump flange usable in conjunction with thetube as shown in Fig. 4 as seen along section line 5-5 in Fig. 4;

Fig. 6 illustrates one half of a stator casing formed from twointerconnecting substantially identical members for a pump constructedin accordance with the invention showing the relative relationships ofthe tubes and the squeezer elements defined by the rollers; and

Fig. 7 is a sectional view taken approximately along the line 7--7 ofFig. 6 and illustrating the sealed casing which surrounds the workingmechanism of the pump of the invention.

First referring to Figs. 1 and 2, it will be noted that the tubeelement'l is provided with end flanges 2 for preventing longitudinaldisplacement of the tube in the casing under the stress of the rollersengaging it.. Further the tube has a longitudinal ridge 4 secured to itswall, said ridge being formed as a continuous elongated bead of, forexample, rectangular cross section, formed with a' multiplicity oftransverse cuts 4 in it. Moreover, two opposite pairs of bosses 3 areprovidedatboth ends of the ridge 4 and spaced a definite short distancefrom the end flanges 2, as shown by the spaces 5. I

On insertion of the tube 1 into the casing, the end bosses 3 arearranged to be compressed to a substantial degree while the ridge 4isstressed. to a lesser degree or allowed to remain substantiallyuncompressed, so as to be capable of free elongation inthe arcuatecondition of the tube, illustrated inFig. l. The spaces 5 between thebosses 3 andflanges Z'serve a similar purpose. The ar rangements. justdescribed serve both .to .reduce the wear 7 and tear of the tube inoperation, and to minimize dis.-

seals at the points of connection ofthe tube 1 with inlet torsion of theend flanges 2, therebypreserving tight fluid and outlet conduits (notshown), it being noted that the, flanges 2, in addition to theretainingfunctionilthereof qdescribed above, preferably also serve as connectingI means foresaid inlet and outlet conduits.

If the retainer ridge 4 were formed by a plurality of entirely separatebosses formed on or secured to the tube wall, this would in effectprovide a' tube element having a wall of non uniform thickness, and thestresses developed in the tube in operation would be correspondingly nonuniform along the length of the tube, resulting in considerablevibration and rapid wear of the tube. According to the inventiontherefore, the ridge 4 is made essentially continuous in character,thereby preserving desirable uniformity in the stresses developedthroughout the length of the tube, while at the same time the transversecuts or slits formed across the continuous ridge permit a fanning-out ofthe ridge (as clearly shown in Fig. 1) so that the arcuate conformationimparted to the tube does not apply undesirable differential tensionstrains between the top and foot of the ridge.

Fig. 3 illustrates a pump assembly according to the invention, includinga further advantageous feature for improving the efliciency of theoperation of the pump. Conventional pumps of thetype specified hereinare subject to limitations in their suction and discharge capacity, asdetermined by the capacity of the tube for restoration to its initial,fully open condition. Thus at the suction end of the tube the tube wallhas to overcome atmospheric pressure which opposes the resilient flexingof the wall and tends to prevent its springing back to its wide-opencondition, while at the discharge end, where the discharge pressureexceeds atmospheric pressure, there is a similar force opposing theresilient flexing of the wall and tending to prevent the tube fromreturning to its normal undeformed condition. Further objects of theinvention, accomplished by means to be now described are to overcomesuch limitations and hence to improve the operating capacity of fluiddisplacement devices of the type specified, beyond that which has beenheretofore found possible.

As shown in Fig. 3, the main resilient tube of the pump is shown at 7 asextending over a partial arc of the cylindrical casing. Over theremaining peripheral arc of the casing there extends an auxiliaryresilient tube 8 of generally similar character to the tube 7, adaptedto be engaged by the rollers 12 during their rotation in the casing. Thetube 8 has one end, such as 10, opening into the interior space of thecasing, while its other end 9 is closed adjacent tube 7 and thereforedoes not communicate with the interior of the casing but is connectedwith the outeratmosphere, e.g. through a check-.valve 11 as shown. Thusthe tube 8 acts as an auxiliary air pump and may be used for increasingor reducingthe air pressure within the casing of the main pump, asdesired. Specifically, depending upon the setting of the check-valve 11to permit the egress or ingress of air from or into the tube 8, theauxiliary pump will act as a vacuum pump to aid the tube wall inspringing back to normal shape and thereby increase the suction capacityof the pump, or as a compressor to increase the air pressure within thecasing acting on the tube wall and thereby to increase the dischargecapacity of the main pump. Where the arrangement shown in Fig. 3 isused, the pump casing should of course be made of a suitable airtightconstruction.

While in Fig. 3 the main pump tube 7 is shown as extending over asmaller arcuate extent than the auxiliary pump tube 8, this relationshipis exemplary only. Thus the main tube 7 may be made to extend over afull 360 of the casing periphery. In the case of the auxiliarytube 8 itwill generally be found satisfactory to have it extend over only afraction of the circumference of the casrng.

Figs. 4 and illustrate a modificationespecially applicable to largecapacity pumps. Such pumps require tubes with considerable wallthickness and subsequent their removal when worn and replacement usuallyinvolves a rather complete dismantling of the pump casing, especially ifthe tube is formed with the ridged reen forced and flanged structureillustrated in Figs. 1 and 2. According to a feature of the inventiontherefore, the

.4 tube 13 has a flange 14 formed at one of its ends only, while theopposite end 16 may be smooth or may preferably include acircumferential groove 15 in it for a purpose to be later described. Theend 16 receives a flange member 14 in groove 15 which cooperates with arecess 17 formed in the connector flange 22 of the pump casing,

1 shown in Fig. 4. In this embodiment, the pump stator amount axiallytowards and away from the other shell,

as by providing a pair of elongated slots through which the boltsattaching it to the common base are passed. The length of thepermissible axial displacement, as determined by the length of theslots, is selected with due regard to the'length of the projectingstator shafting. Further, the displaccable one of the two stator shellsis formed with a wide aperture therein, and a removable cover is adaptedto be fitted thereover to seal the aperture. The purpose of thisarrangement will appear presently. A pair of recesses are provided inthe outlet side of the pump, being dimensioned complementarily to theridges of the flexible tube.

For removing a worn tube element in such a pump and replacing it with anew element, the cover fitted over the perforate displaceable statorshell is first removed, and said shell is then pulled away from theother shell the extent permitted by the elongated bolt slots in itsbase. It will be noted that the rotor shaft remains supported in a partof its bearing means, so that it is at no time placed in anobjectionable overhanging condition. At this stage the flexible tubeelement is released from its compressed condition in the stator and caneasily be removed by rotating the pump rotor in the proper angulardirection. However, since the presence of the ridge on the tubeinterferes with the free passing of the rollers, the movement of saidrollers is preferably aided manually, this being readily accomplished byextending a hand through the wide perforation provided in the statorshell as previously described. After the old tubing has been thuswithdrawn, a fresh tube element is inserted by following a generallyreverse procedure from that just described.

That end of the tube 13 which is not provided with an integral flange'on it is formed with a groove 15 as already indicated. A resilientannular ring or washer may be inserted in the groove after the tube hasbeen inserted so as to provide the missing flange, and the latter willthen be retained in position owing to the pressure of the flange of theconnected conduit.

As. previously indicated, a substantial part of the wear to which theflexible tube is subjected in operation, is ascribable to the suddenrelease of the roller pressure on the tube wall and the sudden return ofthe flattened wall to its normal rounded condition. The maximum stressesdue1to this eflect occur at the outletend of the tube and the resultingwear on the tube material is clearly visible especially on thin-walledtubes, even though its damage to the tube material is actually greatestin thick-walled tubes. The inventio'ri'contemplates steps for overcomingthis las-t'mentioned source of wear and tear, generally comprising theprovision of recesses in the stator casing adjacent the ends of thetube, whereby the tube will be able to initiate the resumption of itsnormalunstressed condition at a point in time slightly in advance of theactual disengagement of each roller from it. Such recesses havebcenillustrated in Fig. 6 of 'the drawings, wherein a pump casing half isshown comprising an intcgral casing 19 eg. of aluminium alloy, includinga toroidal recess 20 for the tube and end flanges 21 and 22. An axialrecess is shownat 23 for the passing of the roller-carrying rotor-shaft12'. According to the features of the invention' now described; thetoroidal chamber 20 is formed with a pair of enlarged recesses 24 and25.

As each roller 12 attains the inner end of either one of the recesses(the particular recess 24 or 25 involved depending on the direction ofrotor rotation used), the compression stress exerted by the rollercommences to be relieved, so that the tube wall is allowed to return toits normal condition in a more gradual manner and damage to the tubematerial is minimized. The recesses such as 24 and 25 may be formedintegrally at casting, or by a subsequent machining operation, as bymilling.

It will be understood that the invention is not limited to the specificembodiments illustrated and described, but modifications may be madetherein within the scope of the claims.

What is claimed is:

1. In a fluid-displacement apparatus of the type described having astator casing, a'tube made from a resilient material and having a radialflange at at least one of its ends, a continuous ridge projecting alonga generatrix over a major extent of the tube with an end of the ridgelongitudinally spaced from said at least one end flange, transverseslits in the ridge to permit bending of the tube in the plane of theridge, bosses projecting from the tube wall adjacent the ends of saidridge and spaced longitudinally of the tube from the related end flange,said stator casing being adapted to fixedly support the tube in anarcuately bent condition with the ridge outwardly of the are and toretain the tube against lateral displacement, each boss and flange beingadapted to engage the casing to retain the tube against longitudinaldisplacement, and at least one squeezer member supported in the casingfor rotational movement about the center of saidarc in squeezingrelation with the tube along the inner wall of the arc to propel fluidfrom one end of said tube to the other.

2. In a fluid-displacement apparatus of the type described having astator casing, atube made from a resilient material and having a radialflange at at least one of its ends, a continuous ridge projecting alonga gener atrix over a major extent of the tube with an end of the ridgelongitudinally spaced from said at least one end flange, transverseslits in the ridge to permit bending of the tube in the planev of theridge, bosses projecting from the tube Wall adjacent the ends of saidridge and spaced longitudinally of the tube from the related end flangeand a second boss diametrically opposite each first boss, said statorcasing being adapted to fixedly support the tube in an arcuately bentcondition with the ridge outwardly of the arc and to retain the tubeagainst lateral displacement, each boss and flange being adapted toengage the casing to retain the tube against longitudinal displacement,and at least one squeezer member supported in the casing for rotationalmovement about the center of said are in squeezing relation with thetube along the inner wall of the arc to propel fluid from one end ofsaid tube to the other.

3. In a fluid-displacement apparatus of the type described having asealed stator casing, a first tube having resilient walls supported overan arcuate path in said casing, a second tube having resilient wallsadapted to be supported along an arcuate path in said casing coplanarWith said first arcuate path and forming an extension of said firstarcuate path, whereby to form a substantially closed substantiallycircular path, said second tube being formed with aperture meansconnecting one endof said second tube with the interior of said casing,vent means connecting the other end of said second tube with the outeratmosphere, and roller means supported in the casing for rotation aboutthe common center of said arcuate paths for squeezingly engaging saidfirst and said second tubes along the walls thereof positioned inwardlyof said arcuate paths so as to propel said fluid through the first tube,and to propel air between the interior of the casing and the atmospherethrough the second tube.

, 4. In a fluid-displacement apparatus of the type described having asealed stator casing, a first tube having resilient walls supported overa first arcuate extent of the casing, a second tube with resilient wallssupported along another arcuate extent of the casing so as to define asub stantially common circumference with said first arcuate extent, saidsecond tube being formed with connecting one end of said second tubewith the casing interior, check valve means connecting the other end ofsaid second tube with the outer atmosphere, and roller means supportedin the casing for rotation about the center of said circumference forsqueezingly engaging said tubes in successive parts of each revolutionso as to displace said fluid means through the first tube, and todisplace air through said second tube.

5. In apparatus as claimed in claim 1, wherein said bosses projectingfrom the tube wall adjacent the respective ends of said ridge and spacedfrom the related end flange have a greater lateral dimension than saidridge.

6. A tube element for use in a fluid displacement apparatus of the typedescribed comprising, a cylindrical tube body made of resilientlyflexible material and having end flanges, a continuous ridge of saidmaterial projecting outwardly from the Wall or said body along ageneratrix thereof over a major extent of said body, transverse slits insaid ridge to permit an arcuate bending of i the body in the plane ofthe ridge, and a pair of retainer bosses adjacent the ends of said ridgeand spaced longitudinally of the tube body from the related end flanges.

7. A tube element as claimed in claim 6, including a second pair ofbosses diametrically opposite said firstnamed pair of bosses.

8. A tube element for use in fluid displacement apparatus of the typedescribed comprising, a cylindrical. tube body made of resilientlyflexible material and having a flange at, one end thereof, an annulargroove formed in the outer periphery of said tube body adjacent theother end thereof, and a continuous ridge of said material projectingoutwardly from the wall of said element along a generatrix thereof overa major extent of said tube body, bosses projecting from the ends ofsaid ridge and spaced longitudinally from the tube end and the flange,and transverse slits in said ridge to permit an arcuate bending of thetube body in the plane of the ridge.

9. Apparatus as claimed in claim 1, wherein said tube has only one endflange, and wherein said casing cornprises two casing sectionsrelatively displaceable transversely of the axis of said are.

10. In the apparatus claimed in claim 2, recessed means in said casingadjacentthe opposite end portions of said tube element to permitmovement of part of said end portions into said recessed means andthereby to permit an easy restoration of the tube walls to the originalunsqueezed condition thereof in said end sections upon disengagement ofsaid squeezer member therefrom.

References Cited in the file of this patent UNITED STATES PATENTS2,403,572 Wittenberg July 9, 1946 2,414,355 Bogoslowsky Jan. 14, 19472,693,766 Seyler Nov. 9, 1954 FOREIGN PATENTS 669,809 Great Britain Apr.9, 1952

